The present invention relates to seating, and more particularly to office and task seating.
To enhance comfort and provide improved ergonomic function, office and task seating is typically provided with a high degree of adjustability. For example, it is common to provide mechanisms for adjusting the height of the seat, the location of the armrest and the degree of lumbar support.
Another common feature provided in some office and task seating is a resilient back recline. The resilient back recline permits the back to tilt or recline rearwardly in a resilient manner under force applied by the occupant. For example, the resilient back recline permits the back to recline rearwardly when an occupant leans backward in the chair. Typically, the back recline mechanism is spring-loaded to provide a desired level of resistance to rearward movement and to return the back to the default or home position when the occupant leans forward.
One particularly advantageous adjustment mechanism is shown in U.S. Pat. No. 4,842,333 to Meiller, which is incorporated herein by reference. The Meiller mechanism operatively links the seat and back portions of the chair so that tilting of the back results in forward and rearward movement of the seat. This mechanism significantly reduces the amount of change in the occupant""s visual and reach zones when he or she reclines in the chair. It also provides substantially uniform spacing between the seat and back through various degrees of inclination, thereby reducing the tendency of the back to xe2x80x9cuntuckxe2x80x9d the occupant""s shirt with each reclining movement.
There is also an ongoing effort to reduce the complexity of operating the control mechanisms for the various components of the chair. Conventional controls typically require operation of numerous knobs, levers and other actuators to adjust the chair. The level of complexity of many conventional controls is such that locating and operating the appropriate actuator for a given adjustment feature can present significant problems. Further, many control mechanisms require substantial physical effort to operate. For example, conventional rotary controls often require numerous complete rotations of a control knob to move the component through its complete range of motion. This effort can be particularly difficult for the aged and those suffering from arthritis, carpal tunnel syndrome or other similar problems. Similar concerns exist in connection with conventional armrest adjustment mechanisms. There is an ongoing need for a reliable and inexpensive adjustment mechanism that is easily operated and provides a high degree of adjustability.
It is also increasingly common to use load bearing fabric in the seat and back of conventional office seating. In load bearing fabric constructions, the load bearing surfaces of the seat and back are defined by a fabric that is stretched over a corresponding opening. The load bearing fabric not only supports the occupant, but also has enough resiliency to provide the desired level of comfort. In typical constructions of this type, no additional cushioning or trim is required in the load bearing regions of the seat and back. Because of the open weave or knit construction of many load bearing fabrics, the seat and back of the load bearing constructions is typically see-through. This means that any lumbar support or other mechanisms secured to the back or seat will be visible during ordinary use of the chair. As a result, there is an ongoing need for a lumbar support that is not only effective in controlling the contour of the lumbar region, but also aesthetically pleasing.
Further, conventional seating manufacturers often provide a line of chairs, rather than a single chair, to meet various specific needs. For example, a line of chairs may include both a task chair and an executive chair; with the task chair designed to meet a lower price point having a relatively small back and sometimes limited adjustability. The executive chair may be design for a higher price point, typically having a larger back and being fully adjustable. This requires the separate design and manufacture of different chair backs, thereby reducing the manufacturing efficiencies associate with larger volumes.
The aforementioned problems are overcome by the present invention wherein a chair is provided with mechanisms that permit a wide range of adjustability of the chair. The chair generally includes an adjustable resilient back recliner mechanism, a pair of adjustable armrests, modular upper back portions and an adjustable lumbar support.
In a first aspect of the invention, the present invention provides a control mechanism that permits simple adjustment of various elements of the chair. In a preferred embodiment, the control mechanism includes a tension knob that is rotated to provide control over the tension in the resilient back recline mechanism, a height push-button that controls the height of the seat and a multi-position limit lever that provides control over the limit of the resilient back recline mechanism.
In a more preferred embodiment, the tension knob provides a full range of adjustment through only 180 degrees of rotation of the knob. More specifically, the chair includes a spring that provides tension in the back recliner mechanism. The tension knob is operatively connected to the spring by a cam, lever and linkage. Rotation of the tension knob causes the cam to pivot the lever, which in turn varies the pre-tension in the spring through operation of the linkage. The tension control mechanism provides a simple and effective control mechanism that is easily moved through its entire range of motion without undue effort.
In another preferred embodiment, the height push button operates a wing that actuates a toggle switch protruding from the top of the upper tube of the support column. The height push button is preferably mounted within the tension control knob, where it is readily accessible. As a result, the height control is easily located and operated.
In another preferred embodiment, recline limit control mechanism includes a lever that is preferably mounted to the shaft of the tension control knob where it is readily accessible. The lever is operatively connected to a rotor that extends and retracts a cable in response to rotation of the lever. The cable is connected to a stop that travels in the path of a trackway on the seat frame to limit movement of the seat frame and consequently the back. The recline limit control mechanism is simple and effective, yet provides a high degree of adjustability to the recline limit. The recline limit lever is mounted adjacent the tension knob and height control so that the various seat controls are arranged in a single location, where they are easily located and operated by the occupant.
In a second aspect, the present invention provides a lumbar support that includes a lumbar pad and a lumbar cam. In a preferred embodiment, the lumbar cam includes lobes of differing dimensions arranged along a shaft. The shaft is rotatably mounted to the lumbar pad, thereby permit adjustment of the contour of the lumbar region by rotation of the lumbar cam. In a more preferred embodiment, the lumbar pad and lumbar cam are exposed and visible to the occupant. In an even more preferred embodiment, the lumbar support is height adjustable. More specifically, the lumbar pad and lumbar cam are movably mounted within a vertical channel. The lumbar support provides a high level of vertical and depth adjustment to the lumbar region through simple rotation of the lumbar cam. The degree of adjustability can easily be adjusted by variations in the lobes of the lumbar cam. Further, the exposed lumbar support is aesthetically pleasing and permits visual inspection of its components.
In a third aspect, the present invention provides an armrest control mechanism that permits adjustment of the height and angle of the armpads. In a preferred embodiment, the armrest control mechanism for each armrest includes a tube movably mounted in an upright and a ratchet mechanism that permits the height of the tube in the upright to be raised simply by lifting the armpads. The ratchet mechanism preferably includes a reset mechanism that permits each tube to be lowered only after it has been raised to its upper extreme. The armrest height control mechanism provides a high degree of vertical adjustment and, because there are no actuators, is easily operated simply by lifting or lowering the armpads.
The armrest control mechanism also preferably includes an armpad pivot mechanism that permits pivotal adjustment of the armpads. The pivot mechanism generally includes a lower plug that carries the plunger of the ratchet mechanism and an upper plug that is affixed to the tube and rotatably mounted to the lower plug. The pivot mechanism permits the tube, and hence the armpad, to be rotated without rotating the plunger. This mechanism provides a high degree of adjustability and is easily incorporated with the armrest height control mechanism.
In a fourth aspect, the present invention provides a modular back assembly that permits variation in the overall shape of the back through the installation of interchangeable upper back portion components. In a preferred embodiment, the back defines a mounting platform that is adapted to receive any of a variety of upper back portions through a snap-fit connection. The mounting platform is preferably disposed at the upper extreme of the back such that the overall shape and height of the back is readily varied by differently shaped upper back portion components. The modular upper back portion permits inexpensive variation in the overall shape of the back, thereby eliminating the need for the design, development and manufacture of entirely different backs to meet different price points.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.